The use of trichloromonofluoromethane ("CFC-11") in the production of closed cell, rigid polyurethane and polyisocyanurate foams is well known (see, e.g., U.S. Pat. Nos. 3,072,582; 3,091,551; 3,153,002; 3,524,825; 3,846,347; and 4,248,975). Recently, the urethane foam industry has been investigating methods for reducing the amount of CFC-11 used in producing rigid foams.
U.S. Pat. No. 3,745,203 describes the production of polyurethane moldings using a mixture of two volatile blowing agents. The least volatile of the blowing agents has a boiling point of from 30.degree. F. to 120.degree. F., while the more volatile blowing agent in the mixture has a boiling point of from -50.degree. F. to 500.degree. F. The difference between the boiling points of the two blowing agents in the mixture is from 30.degree. F. to 150.degree. F.
German Auslegeschrift 1,288,312 describes the use of an azeotrope of CFC-11 and isopentane as a blowing agent (U.S. Pat. No. 3,249,546 describes the azeotrope itself). o blowing agent
U.S. Pat. No. 4,055,521 describes a which is a mixture of CFC-11, isopentane, and methylene chloride.
U.S. Pat. No. 3,391,093 describes the use of halogenated blowing agents which generally have boiling points below about 80.degree. F. for producing polyurethane foams. The reference does indicate that low molecular weight hydrocarbon gases can be used with the halogenated blowing agents. U.S. Pat. No. 4,795,763 broadly indicates that mixtures of halohydrocarbons and hydrocarbons can be used as blowing agents for polyurethane foams.
It has also been suggested that 2,2-dichloro-1,1,1-trifluoroethane ("HCFC-123") and 1,1-dichloro-1-fluoroethane ("HCFC-141") can be used as blowing agents for rigid polyurethane foams (See, e.g., Dishart et al, "The DuPont Program on Fluorocarbon Alternative Blowing Agents for Polyurethane Foams," POLYURETHANES WORLD CONGRESS 1987-SEPT. 29-OCT. 2, 1987, pages 59-66, and U.S. Pat. No. 4,076,644).
The use of a mixture of a chlorofluorocarbon having an atmospheric boiling point of from about 74.degree. F. to about 120.degree. F. and an alkyl alkanoate having a molecular weight of no more than about 88 as a blowing agent has been described in U.S. application Ser. No. 321,032, filed on Mar. 9, 1989. Among the chlorofluorocarbons described are HCFC 123 and HCFC 141b. Among the alkyl alkanoates described is methyl formate.
Finally, various compositions based on halogenated hydrocarbons are known for use as cleaning solvents. For example, U.S. Pat. No. 4,055,507 describes the use of an azeotropic mixture of 1,2-dichloro-1,1-difluoroethane and 3-methylpentane. Japanese 1,141,995 (abstract only) describes an azeotropic mixture of 67 to 87% by weight of HCFC-123 and 13 to 33% by weight of 2-methylbutane. Japanese 1,141,996 (abstract only) describes an azeotropic mixture of HCFC-141b and a member selected from the group n-pentane, 2-methylbutane and 2,2-dimethylbutane.